The present invention relates to apparatus for making particle ice in a refrigerator for domestic or household use and particularly icemakers of the type for continuously making ice used for cooling beverages. Icemakers of this type typically form ice by a timed water fill of a mold and upon freezing of the water in the mold harvest by mechanically removing the ice from the mold and permitting the particles to fall into a collector tray or bin.
The timing of the waterfill is typically controlled by a motor driven timing cam which activates a switch for controlling the opening and closing of an electrically operated water fill valve. Heretofore, it has been the practice to time the valve opening by providing a snap acting microswitch mounted on a bracket which is adjustably positioned on the icemaker housing with respect to the motor driven timing cam. The bracket is adjusted with respect to the cam for calibrating the time between actuation and deactuation of the microswitch for a given cam profile and rate of rotation. This manner of setting the timing for the opening and closing of the switch for the electric waterfill valve has proven to be costly and troublesome in high volume manufacturing. In particular, where the microswitch is calibrated for actuation upon an increase in cam profile, the deactuation must then occur on a decrease in cam profile; and, the time to fill the mold is determined by the rate of rotation of the cam and the shape of the cam with respect to the deadband or difference between actuation and deactuation of the microswitch. In a typical microswitch, the deadband of the switch snap acting blade mechanism is variable and typically is not repeatable within a degree of a accuracy required to properly control valve open time for controlled waterfill of the mold. Accordingly, it has proven extremely difficult to calibrate the microswitch against a given constantly rotating cam profile to provide precisely controlled timing of opening and closing of the waterfill valve in response to actuation and deactuation of a snap acting microswitch.
It has thus been desired to find a simple and low cost way or means of providing precisely timed opening of a flow-calibrated valve for measured fill of a mold for forming ice in a refrigerator icemaker.